Prefabrication experiments - 154 - open building - 05 - Floor cassettes

Efficient industrialized building systems relate open building theory by means of their adaptability while being easily assembled and mitigating irritants associated with on-site construction. Irritants include time and labour intensive processes that are contingent to waste and climate unpredictability. Reducing these irritants involves spending less time on site and more time in a value adding climate and quality controlled environment. Further, modular subassemblies such as walls, floors, or service cores can reduce the on-site complexities associated with system coordination.

The floor (or roof) cassette is an assembly designed and manufactured to order using industrialized pieces. Part of the building industry for many years, a great number of cassette systems are on the market, however the systems which employ open web joists are of particular relevance to open building. The open web or hollow core facilitates system integration and the potential relocation of systems in two directions as a network of interstitial space is created. In systems other than stressed-skin systems, the open web joists are stabilised laterally by timber or steel bracing. Cassettes are packed flat and delivered and then easily combined to create floor plates both safely and efficiently.

Both unidirectional and two directional floor plates are possible as the cassettes sit on a major grid of structural beams. A German manufacturer Kielsteg has developed a particularly interesting system using a folded accordion-like core. Competing with mass timber floor panels the hollowed core is a more rational use of timber and makes the structure lighter.  The hollow core and the open web joists systems make the structure easier to transport. The cassettes thickness varies according to spans. Usually delivered as an under-floor and a ceiling framing most finish work is left to on-site workers. Many manufactures as is the case with the Colli system from Australia now offer a building information modeling service making mechanical systems an integral part of the cassette further simplifying the entanglement usually associated with floor construction. Less site-intensive than regular floor joist systems the cassettes are positioned in place simply using a crane. One of the great advantages over standard platform construction is the inbuilt stability of the cassettes once they are positioned in place.

Colli System (left) and Kielsteg system (right)

Prefabrication experiments - 153 - Open Building - 04 - M.A.D.I. Unfolding House

According to a report published by the Preparatory Committee for the United Nations Conference on Housing and Sustainable Urban Development (Habitat III) in June 2016 at least 2 billion more people will require adequate housing by 2030. As global urbanization continues at an extraordinary rate, more alternatives for affordable, flexible and adaptable housing solutions are required. The problem of adequate and flexible housing solutions makes a case for rapidly deployed systems that are agile enough to be established in differing geographic and social contexts.

Architectural history provides a varied corpus of ideas for housing developed specifically for times of crisis. The inclination to serve the 99% without access to design services is a persisting leitmotif in architecture. Architects proposed innovative deployment strategies such as collapsibility to effectively provide simple dwellings. From Eero Saarinen’s unfolding house to Herbert Yates plydom agriculture workers’ housing, folding and unfolding an adaptable form of mass housing integrated both architectural discourse and prototype production.

Looking to leverage both contemporary crisis and the essence of quickly deployable structures, Italian architect Renato Vidal has developed an unfolding A-frame. Combining two archetypes of architecture, folding and the simplicity of the A-frame structure, the architect develops a simple multi-purpose building system that can be transported and adjusted to any site. A hinged panel composite system of cross-laminated timber with a metal facing begins as a 20-foot standard container.  Once it arrives on site, the container is literally «unfolded» by lifting the ridge into place which produces a compression triangle arch positioning the oblique sections in place with the U-shaped floor and lateral half-walls acting as a tie beam. Five standard sized 20-foot sections are juxtaposed to form the basic 80 square meter dwelling and aligning additional sections results in dwellings of various sizes. Placed on point foundations such as screw-in piles, the structure can be moved and removed as needed reducing site disturbance. Multiple organisations are possible both in terms of size and planning as the a-frame’s interior volume can be designed to suite client needs. Although not proposed as such by the architect, the gable wall ends could potentially by designed and even built on site to suit local materials and individual desires.

Renato Vidal's M.A.D.I. Unfolding House

Prefabrication experiments - 152 - Open Building - 03 - Levitt Technology Corp's Manufactured Row-housing System

Operation breakthrough launched by the US government’s Housing and Urban Development in 1969 was one the 20th century’s important vectors for promoting innovative urban strategies as well as  the industrialization of construction. Bringing together academics, architects and industries to project the future of housing produced a diversity of prototypes. From National Homes’ post-tensioned superframes to the iconic Shelley checkerboard stacking, all sought to Increase efficiency and productivity in the construction industry while offering planning flexibility to suit the multiple and varying needs of modern lifestyles. Although not usually linked to industrialized building systems, even William Levitt and Sons proposed a building system that combined the ideal of manufactured sub-assemblies with the need for personalization. 

William J. Levitt is best known for his onsite standardized construction methods synonymous with post World War 2 American suburbanization. The onsite assembly line specialized construction tasks and had workers follow each other from house to house replicating specified and specialized tasks. A model of process efficiency Levitt controlled every part of the building process from procuring elements and building products directly from manufacturers to the incremental scheduling of each house. Levitt and sons produced thousands of uniform dwellings. Even as this process was perfected, operation breakthrough allowed Levitt to imagine a reformed building method combining standard parts into an open model of industrialization.

Levitt Technology Corporation worked in partnership with architects B.A. Berkus and Associates along with manufacturers and suppliers. The proposal employed staggered volumetric singlewides as the basic modular building blocks.  Identically dimensioned service core (wet) boxes with standardized plans and served space boxes (dry) with variable plans were juxtaposed or stacked in a linear massing of solids and voids. Elements such as entry door porticoes, bay windows, window canopies and patio or deck volumes could be added to the basic box system to vary each dwelling’s identity; a type of mass customization based on user preferences. Rhythmic extrusions and intrusions projected a dynamic streetscape while the decorative elements concealed the proposal’s repetitive nature.  The simple timber stick construction leveraged the heritage of American building culture with standardized mobile home production to produce replicable medium density low-rise housing process.

above left: Shelley Construction System; below left: National Homes' Superframes; right: Levitt Technology Corporation's System